Diaper Ice Pack

Make a leak resistant ice pack with water and a diaper. Just pour some water into the bottom of an unused diaper. The absorbent material will turn into a gel-like substance. Scoop out the gel, stick it in a Ziploc bag, and you’re all set.
http://lifehacker.com/make-a-leak-resistant-ice-pack-with-water-and-a-diaper-1634143048